CN108702117B

CN108702117B - Control device for AC motor

Info

Publication number: CN108702117B
Application number: CN201780012997.4A
Authority: CN
Inventors: 中井康裕
Original assignee: Denso Corp
Current assignee: Denso Corp
Priority date: 2016-02-24
Filing date: 2017-02-22
Publication date: 2021-05-28
Anticipated expiration: 2037-02-22
Also published as: JP6540538B2; US10432123B2; JP2017153227A; CN108702117A; US20190052211A1; WO2017146090A1

Abstract

The current controller (30) inverts the driving current by fundamental current control and high-order current controlThe drive signal of the device (40) is calculated. 5 th/7 th voltage command calculation units (55, 75) extract the high-order dq conversion values of 5 th and 7 th components from the actual current and the 5 th and 7 th dq axis current command values Id_k ^＊、Iq_k ^＊A consistent feedback control is performed so as to control the voltage command vector Vd of 5 th order/7 th order_k ^＊、Vq_k ^＊The calculation was performed, k being 5 and 7. 5 th/7 th order vector conversion units (57, 77) convert the 5 th/7 th order voltage command vector Vd calculated by the 5 th/7 th order voltage command calculation unit_k ^＊、Vq_k ^＊A higher order vector conversion process including rotation conversion for rotating a higher order vector is performed to make the higher order voltage vector on the higher order dq coordinate coincide with the phase of the higher order current vector.

Description

Control device for AC motor

Technical Field

The present invention relates to a control technique for an ac motor, which controls energization of a multiphase ac motor by current feedback control.

Background

It is known that in the vector control of a multiphase ac motor, high-order components are superimposed on the fundamental wave components of the phase currents due to the excitation unevenness of the rotor magnets constituting the ac motor and the shapes of the rotor and the stator. For example, a motor control device disclosed in patent document 1 performs feedback control on a high-order current command value set to 0 by converting the high-order dq of the high-order component of the actual current directly.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 3809783

Disclosure of Invention

Technical problem to be solved by the invention

The high-order dq-axis current control unit of the motor control device disclosed in "the first embodiment" of patent document 1 is configured to control the actual currents idh and iqh of the high-order dq axis and the current command value idh^＊＝0、iqh^＊High-order dq-axis voltage command value vdh consistent with 0^＊、vqh^＊And (6) performing operation. Specific controlAlthough not shown, the high-order dq-axis current control unit is assumed to perform feedback control by performing proportional-integral computation on the d-axis and q-axis, respectively, as in the fundamental current control.

However, in general, the phase of the voltage vector and the phase of the current vector do not match in the dq-axis coordinate, and a phase difference exists. When the phase difference becomes large, the motor control may become unstable depending on the structure and characteristics of the ac motor.

The invention aims to provide a control technology of an alternating current motor, which enables the phases of a high-order voltage vector and a high-order current vector to be consistent and enables the control to be stable.

Technical scheme for solving technical problem

An ac motor control device according to an aspect of the present invention includes: an inverter (40) that supplies the power converted by the operation of the plurality of switching elements (41-46) to a multi-phase AC motor (80); and a current controller (30) for controlling the energization of the AC motor.

The current controller operates a drive signal for driving the inverter by "fundamental current control" and "high-order current control". The "fundamental current control" is a control in which the 1 st order component of the actual current subjected to the feedback control is matched with the fundamental current command vector on the dq coordinate. The "high-order current control" is a control of matching 1 or more high-order components of a specific order extracted from the actual current subjected to the feedback control with the high-order current command vector on the high-order dq coordinate.

The current controller has high-order voltage command calculation units (55, 75) and high-order vector conversion units (57, 77).

The high-order voltage command calculation unit calculates a high-order voltage command vector by feedback control in which a high-order dq conversion value of a high-order component of a specific order extracted from an actual current is matched with a high-order dq-axis current command value.

The higher order vector conversion section performs a "higher order vector conversion process" including "rotation conversion" for rotating the higher order vector. Specifically, the higher order vector conversion unit rotates the higher order vector such that the phase of the higher order voltage vector at the higher order dq coordinate matches the phase of the higher order current vector with respect to the higher order current vector deviation input to the higher order voltage command calculation unit or the higher order voltage command vector calculated by the higher order voltage command calculation unit.

Thus, the higher order vector conversion section performs the higher order vector conversion process on the higher order current vector or the higher order voltage command vector. Therefore, the control device of the invention can stabilize the control of the motor.

In addition, the high-order vector conversion processing may include "amplitude conversion" in which a gain other than 1 times is multiplied by the amplitude of the high-order vector, in addition to the rotation conversion.

The current controller further comprises a conversion amount setting unit (56, 76), and the conversion amount setting unit (56, 76) sets a conversion amount in the high-order vector conversion processing, that is, a rotation angle of the rotation conversion and a gain of the amplitude conversion, based on the fundamental wave current command value and the rotation speed of the alternating current motor.

In this way, the current controller sets the rotation angle of the rotation conversion and the gain of the amplitude conversion in accordance with the operation state of the ac motor such as the current value and the rotation speed. Thus, the responsiveness of the feedback control of the control device of the present invention can be constant regardless of the operating point.

Drawings

Fig. 1 is a schematic configuration diagram showing a motor generator drive system to which a control device for an ac motor according to a first embodiment is applied.

Fig. 2 is a control block diagram of the current controller.

Fig. 3 is a flowchart showing an outline of the fundamental wave current control processing.

Fig. 4 is a diagram showing a relationship between a fixed coordinate system and a dq coordinate system with respect to a fundamental wave.

Fig. 5 is a diagram showing a relationship between a fixed coordinate system and a dq coordinate system with respect to the phase current-5 order component.

Fig. 6 is a control block diagram illustrating dq conversion and high-order dq conversion.

Fig. 7A is a diagram illustrating a smoothing process of a torque command value by the command value filter.

Fig. 7B is a schematic diagram showing a frequency spectrum of the actual torque and the torque command value before and after the filter processing.

Fig. 8A is a diagram showing a phase difference between a voltage vector and a current vector.

Fig. 8B is a schematic diagram when only rotation conversion is performed in the high-order vector conversion processing.

Fig. 8C is a schematic diagram when rotation conversion and amplitude conversion are performed simultaneously in the high-order vector conversion processing.

Detailed Description

Hereinafter, an embodiment of a control device for an ac motor, which is one embodiment of the present invention, will be described with reference to the drawings. The ac motor control device according to the embodiment is a device that controls energization of a three-phase ac motor, that is, a motor generator (hereinafter, referred to as "MG") as a power source of a hybrid vehicle or an electric vehicle (hereinafter, referred to as "MG drive system"). In the embodiments, "MG" and "MG control device" correspond to "a multi-phase ac motor" and "a control device for an ac motor" described in the claims.

(first embodiment)

(System configuration)

The overall configuration of the MG drive system according to the present embodiment will be described with reference to fig. 1. In fig. 1, a system including one MG is illustrated. The MG drive system 99 mounted on the hybrid vehicle converts the direct current of the battery 25, which is a rechargeable battery that can be charged and discharged, into three-phase alternating current through the inverter 40. The MG drive system 99 supplies three-phase ac power to the MG80 to drive the MG 80. The MG control device 10 of the MG drive system 99 includes a current controller 30 and an inverter 40.

The MG control device 10 of the present embodiment may be applied to an MG drive system including two or more MGs.

Six switching elements 41 to 46 of upper and lower arms of the inverter 40 are bridge-connected. Specifically, the

switching elements

41, 42, and 43 are switching elements of U-phase, V-phase, and W-phase upper arms, respectively.

Switching elements

44, 45, and 46 are switching elements of U-phase, V-phase, and W-phase lower arm, respectively. The switching elements 41 to 46 are formed of, for example, IGBTs (Insulated Gate Bipolar transistors), and reflux diodes that allow a current to flow from a low potential side to a high potential side are connected in parallel.

The inverter 40 operates the switching elements 41 to 46 based on the PWM signals UU, UL, VU, VL, WU, WL from the current controller 30, and converts the direct current into a three-phase alternating current. The inverter 40 applies phase voltages Vu, Vv, Vw corresponding to the voltage command calculated by the current controller 30 to the

phase windings

81, 82, 83 of the MG 80.

A smoothing capacitor 47 for smoothing an input voltage is provided at an input portion of the inverter 40. The input voltage sensor 48 detects the inverter input voltage Vinv. Further, a boost converter may be provided between the battery 25 and the inverter 40.

MG80 is a permanent magnet synchronous three-phase ac motor, for example. In the present embodiment, MG80 is mounted on a hybrid vehicle including engine 91. MG80 has both a function as a motor and a function as a generator. Specifically, the MG80 functions as an electric motor that generates torque for driving the drive wheels 95. MG80 has a function as a generator for recovering torque energy transmitted from engine 91 and drive wheels 95 by power generation. The MG80 is connected to an axle 94 via a gear 93 such as a transmission. The torque generated by MG80 rotates an axle 94 via a gear 93. Thereby, the driving wheel 95 is driven.

A current sensor for detecting phase currents is provided on a current path connected to two of the three-

phase windings

81, 82, and 83 of the MG 80. In the embodiment shown in the example of fig. 1,

current sensors

62 and 63 for detecting the phase currents Iv and Iw are provided on the current paths connected to the V-phase winding 82 and the W-phase winding 83, respectively. Thus, in the present embodiment, the U-phase current Iu is estimated based on kirchhoff's law. In addition, the current detection method can detect the current of any two phases. As another method, currents of three phases may be detected. Alternatively, a method of estimating the currents of the other two phases based on the current detection value of one phase may be employed.

The electrical angle θ e corresponding to the rotor position of the MG80 is detected by a position sensor 85 such as a resolver.

The torque command generator 20 generates a torque command value Trq of MG80^＊. In the present embodiment, the operating state of the vehicle is comprehensively determined based on various input signals, and only functional units for torque command generation in the vehicle control current for controlling the driving of the vehicle are shown. In the present embodiment, the control circuits related to the other functional units of the vehicle control circuit, the battery 25, and the engine 91, and the like are not illustrated or described.

The current controller 30 acquires the inverter input voltage Vinv, the phase currents Iv and Iw, and the electrical angle θ e detected by the sensors. Further, a torque command value Trq is input from the torque command generator 20, which is a higher-order control circuit, to the current controller 30^＊. Based on the above information, the current controller 30 calculates PWM signals UU, UL, VU, VL, WU, and WL as drive signals for driving the inverter 40. The inverter 40 converts electric power by operating the switching elements 41 to 46 based on the PWM signals UU, UL, VU, VL, WU, and WL. The inverter 40 outputs electric power corresponding to the command of the current controller 30 to the MG 80.

In addition, the drive signal for driving the inverter 40 is not limited to the PWM signal. The drive signal may be a pulse waveform or the like, for example. However, it is desirable that the current flowing to MG80 contain no higher-order components as much as possible.

However, in the energization control of the MG80, a high-order component is superimposed on the fundamental wave component of the phase current due to the excitation unevenness of the rotor magnets constituting the MG80, the shapes of the rotor and the stator, and the like. As a result, the loss and NV characteristics (characteristics of noise and vibration) are affected by the ratio of the higher-order component to the fundamental wave.

In particular, in MG drive system 99 of a hybrid vehicle or the like, which is strictly required for loss and NV characteristics, it is required to control a high-order current of a specific order to a desired value. Here, the desired value may be required to be 0 depending on an operation point reflecting the operating condition of the vehicle, a required characteristic of the vehicle, and the like. In addition, it may be desirable to set the desired value to a predetermined value other than 0.

Patent document 1 (japanese patent No. 3809783) discloses a motor control device that performs feedback control of a high-order current command value set to 0 by converting a high-order dq of a high-order component of an actual current directly into a current.

The MG control device 10 of the present embodiment includes a current controller 30 for solving the technical problem in the disclosure technology of patent document 1. The configuration of the current controller 30 according to the present embodiment will be described in detail below.

(Structure and action of Current controller)

The structure and operation of the current controller 30 according to the present embodiment will be described with reference to fig. 2 to 8.

The current controller 30 is constituted by a microcomputer or the like, and includes a CPU, ROM, I/O, and a bus bar connecting the above elements. The current controller 30 performs the following control: control (control of software processing) for causing a CPU to execute a program stored in advance in a ROM or the like; and control of dedicated electronic circuits (control of hardware processing).

In fig. 2, a control block of the current controller 30 is illustrated. The current controller 30 has a control block of a fundamental current control system and a control block of a higher-order current control system. The "fundamental current control" is a control in which the 1 st order component of the actual current subjected to the feedback control is matched with the fundamental current command vector on the dq coordinate. The "high-order current control" is a control of matching 1 or more high-order components of a specific order extracted from the actual current subjected to the feedback control with the high-order current command vector on the high-order dq coordinate.

In the present embodiment in which the driving object is a three-phase ac motor, an example in which the specific order is 5 steps and 7 steps is shown. Therefore, the control block of the higher-order current control system is also divided into control blocks of the 5-order current control system and the 7-order current control system. In addition, the phase current 5 th order component is a component having a frequency five times as large as the phase current 1 st order component. The phase current 7 th order component is a component having a frequency seven times as high as the phase current 1 th order component.

For the reference symbols of the respective control blocks, two-bit numbers are used. Specifically, in the reference symbols, the second digit of the two digits is "1" in the fundamental current control system, "5" in the 5 th order current control system, and "7" in the 7 th order current control system, and the first digit corresponds to each number.

In addition, the second two-digit number of the reference symbols of the control blocks that process the feedback information from the

current sensors

62 and 63 and the position sensor 85 is "3". First, the differentiator 38 not included in each control system will be described. The differentiator 38 calculates an electrical angular velocity ω (deg/s) by temporally differentiating the electrical angle θ e detected by the position sensor 85. The proportional constant is multiplied by the electrical angular velocity ω to calculate the rotation speed n (rpm). Therefore, in the present specification, "the electric angular velocity ω is converted into the rotational speed" and is represented as "the rotational speed ω" while omitting the description.

Hereinafter, the overall outline of each control block will be described, and then the characteristic portions will be described in detail.

First, a configuration related to the fundamental wave current control will be described.

The control block of the fundamental current control system includes a command value filter 11, a fundamental current command generating unit 12, a fundamental current deviation calculating unit 13, a fundamental voltage command calculating unit 15, a three-phase converting unit 18, a higher-order voltage component superimposing unit 19, and an actual current dq converting unit 36.

The command value filter 11 is a 1 st order lag filter. The command value filter 11 compares the torque command value Trq acquired from the torque command generator 20 with a command value^＊And (6) carrying out filtering processing. The technical meaning of the filtering process will be described in detail later.

The fundamental current command generation unit 12 generates a fundamental current command based on the filtered torque command value Trq processed by the command value filter 11^＊F, generating a fundamental current command value Id in dq coordinates^＊、Iq^＊. The current command value generation processing may refer to a table (with correspondence) stored in advance in a storage medium, for exampleData), or may be calculated using a predetermined equation or the like. The same applies to the respective high-order current instruction generation processes of 5 th and 7 th orders.

Hereinafter, regarding the current or voltage in the dq-axis coordinate, there are a case of being expressed by "a current value or a voltage value" and a case of being expressed by "a current vector or a voltage vector". The principle is as follows: when the "value" is used, a d-axis current value (or voltage value) which is a scalar and a q-axis current value (or voltage value) which is a scalar are focused. On the other hand, when the vector is expressed, a vector in which an amplitude and a phase are determined on coordinates is focused. In particular, in the high-order vector conversion process of the high-order current control, "vector" is used for referring to the phase.

In the description of the current controller 30 based on the vector control, it is considered that the "vector" is preferably used for all of the dq-axis currents or the dq-axis voltages. However, in this specification, in order to avoid redundancy of description, except for the case where it is obviously more appropriate to use the "vector", the "value" is used.

The actual current dq conversion unit 36 converts the coordinates of the phase currents Iv and Iw in the fixed coordinate system detected by the

current sensors

62 and 63 into the dq-axis currents Id and Iq in the rotating coordinate system based on the electrical angle θ e detected by the position sensor 85. The dq-axis currents Id and Iq are fed back to the fundamental wave current deviation calculation unit 13 as actual currents that actually supply the MG 80.

Here, the phase currents Iv and Iw are superimposed with high-order components such as phase current 5-order component, phase current 7-order component, and the like on the phase current 1-order component. Strictly speaking, there is a possibility that (6n ± 1) -order components (n is a natural number) of 11 th order, 13 th order, 17 th order, 19 th order, and the like are superimposed in addition to 5 th order and 7 th order. In the present embodiment, for the sake of easy understanding of the description, components of 11 th order or more are omitted, and only phase current 5 th order components and phase current 7 th order components will be described. The phase current 5 th order component and the phase current 7 th order component described above are converted into a dq-axis current 6 th order component by dq conversion.

In the following description, the negative order is defined, and the expressions such as "phase current (-5) order", "dq axis (-6) order" are used. On the other hand, the number of orders is expressed as an absolute value without distinction between positive and negative.

The fundamental current deviation calculation unit 13 controls the fundamental current command value Id generated by the fundamental current command generation unit 12^＊、Iq^＊Fundamental current deviations Δ Id and Δ Iq, which are differences between the actual currents Id and Iq fed back from the actual current dq conversion unit 36, are calculated. As described later, the fundamental current deviations Δ Id and Δ Iq correspond to the 6 th order component of the dq coordinate system.

The fundamental wave voltage command operation unit 15 is constituted by a PI controller, for example. The fundamental wave voltage command calculation unit 15 calculates the dq-axis voltage command value Vd for the fundamental wave by PI control so that the fundamental wave current deviations Δ Id and Δ Iq converge to 0, respectively^＊、Vq^＊And (6) performing operation.

Three-phase conversion unit 18 converts the dq-axis voltage command value Vd of the fundamental wave based on the electrical angle θ e^＊、Vq^＊Coordinate conversion to three-phase voltage command value Vu^＊、Vv^＊、Vw^＊. Hereinafter, the three-phase voltage command value "Vu^＊、Vv^＊、Vw^＊"is denoted as" Vuvw^＊". Likewise, by "Vuvw₅ ^＊＊、Vuvw₇ ^＊＊"indicates the higher-order three-phase voltage command value.

The high-order voltage component superimposing unit 19 calculates the three-phase voltage command values Vuvw of 5 th order and 7 th order calculated by the respective control blocks of the 5 th order and 7 th order current control systems₅ ^＊＊、Vuvw₇ ^＊＊Three-phase voltage command value Vuvw superimposed on fundamental wave^＊. In fig. 2, for convenience of illustration, the three-phase voltage command values Vuvw of 5 th order are shown first₅ ^＊＊And three-phase voltage command value Vuvw of order 7₇ ^＊＊Adding and then adding the three-phase voltage command value Vuvw of the fundamental wave^＊Examples of (3). That is, fig. 2 shows an example in which three-phase voltage command values are added in two stages. In addition, the addition method is not limited to this. As another addition method, the addition may be performed in one stage regardless of the order of addition.

In fig. 2, a control block between the high-order voltage component superimposing section 19 and the inverter 40 is omitted. Between them, a voltage duty ratio conversion section and a PWM signal generation section are provided.

The voltage duty ratio conversion part converts the three-phase voltage command value Vuvw of the fundamental wave^＊Converted to a commanded duty cycle. In the above conversion operation, information of the inverter input voltage Vinv is used. The PWM signal generator calculates PWM signals UU, UL, VU, VL, WU, WL by PWM modulation based on the command duty ratio, and outputs the PWM signals to the inverter 40. Since PWM control is a known technique, detailed description thereof is omitted.

Fig. 3 illustrates an outline flow of the fundamental current control process executed by the control block of the fundamental current control system. Note that a symbol "S" in the flowchart indicates a processing step (step).

The command value filter 11 performs a torque command filter process (step S1).

Fundamental current command generation unit 12 generates a torque command value Trq based on the filtered torque command value Trq^＊F, making a fundamental current command value Id in dq coordinates^＊、Iq^＊The generation processing (step S2).

The actual current dq conversion unit 36 and the fundamental wave current deviation calculation unit 13 provide the fundamental wave current command value Id with respect to the fundamental wave current command value^＊、Iq^＊And carrying out current feedback processing. Next, the fundamental wave voltage command operation unit 15 gives the dq-axis voltage command value Vd to the fundamental wave^＊、Vq^＊An operation is performed (step S3).

Three-phase conversion unit 18 outputs dq-axis voltage command value Vd to the fundamental wave^＊、Vq^＊Coordinate conversion is performed, and phase voltage calculation processing is performed (step S4).

The PWM signal generation unit performs PWM modulation (step S5).

Next, a structure related to the high-order current control will be described.

The control block of the 5-step current control system includes a 5-step current command generating unit 52, a 5-step current deviation calculating unit 53, a 5-step dq converting unit 54, a 5-step voltage command calculating unit 55, a conversion amount setting unit 56, a 5-step voltage vector converting unit 57, and a three-phase converting unit 58.

The 5-step current command generation unit 52 generates a torque command value Trq based on the torque command value Trq^＊And the rotation speed ω of MG80, and generates a 5-step dq-axis current command value Id by referring to a map (data with a correspondence relationship) or the like₅ ^＊、Iq₅ ^＊. As described above, the desired value of the 5 th order current can be set to "Id" according to the loss and NV characteristics required by the system₅ ^＊＝0、Iq₅ ^＊A target value other than 0 "may be set.

The 5 th-order dq conversion unit 54 converts the fundamental current deviations Δ Id and Δ Iq (6 th-order component of the dq coordinate system) to a 5 th-order dq coordinate system, which is a higher-order dq coordinate system, based on "-5 θ e", which is a (-5) multiple of the electrical angle θ e. Thus, the 5-step dq conversion unit 54 extracts the phase current 5-step component included in the actual current. Hereinafter, the order of "5-order dq conversion" or the like is expressed by an absolute value of the order of the fixed coordinate system. The negative sign of "-5 θ e" is referred to as follows.

The 5-step current deviation calculation unit 53 applies the 5-step dq-axis current command value Id generated by the 5-step current command generation unit 52₅ ^＊、Iq₅ ^＊A 5-order current deviation Δ Id which is a difference value from a 5-order dq conversion value obtained by the 5-order dq conversion unit 54 performing the high-order dq conversion on the 5-order dq conversion₅、ΔIq₅And (6) performing calculation.

Here, the output from the fundamental wave current deviation calculation unit 13 reflects the value calculated by making the actual current values Id, Iq negative. Therefore, the input from the 5 th-order dq conversion unit 54 to the 5 th-order current deviation calculation unit 53 is represented by a positive sign, minus a negative number.

The 5-stage voltage command calculation unit 55 is constituted by, for example, a PI controller. A 5-step voltage command calculation part 55 for calculating 5-step current deviation DeltaId₅、ΔIq₅Converging to 0, the 5-step voltage command vector Vd is calculated by PI control₅ ^＊、Vq₅ ^＊And (6) performing operation.

The 5 th order voltage vector conversion unit 57 converts the 5 th order voltage command vector Vd calculated by the 5 th order voltage command calculation unit 55 to the 5 th order dq coordinate₅ ^＊、Vq₅ ^＊Performing "high order vectorVolume conversion processing ". The 5-step voltage vector conversion unit 57 converts the converted 5-step dq-axis voltage command vector Vd₅ ^＊＊、Vq₅ ^＊＊And (6) outputting.

In the high-order vector conversion processing, at least: make 5-order voltage command vector Vd₅ ^＊、Vq₅ ^＊With a predetermined rotation angle phi₅"rotational translation" of rotation. Rotation angle phi of rotation conversion₅Excluding 2n π (n is an integer) (rad).

The high-order vector conversion processing may include multiplying a gain G5 other than 1 by a voltage command vector Vd of order 5₅ ^＊、Vq₅ ^＊Amplitude conversion of the amplitude of (a). In other words, in the high-order vector conversion process, when the gain G5 is 1 time, the process is a process in which only the rotation conversion is performed without amplitude conversion.

The conversion amount of the higher-order vector conversion process, i.e., the rotation angle phi of the rotation conversion₅And gain G of amplitude conversion₅Is set by the conversion amount setting section 56. In the present embodiment, the conversion amount setting unit 56 sets the conversion amount based on the fundamental wave current command value Id^＊、Iq^＊And rotation speed omega, rotation angle phi converted to rotation₅And gain G of amplitude conversion₅The setting is performed.

The technical meaning of the high-order vector conversion processing will be described in detail later.

Three-phase conversion unit 58 converts the high-order vector into dq-axis voltage command value Vd on the basis of "-5 θ e", which is a (-5) multiple of electrical angle θ e₅ ^＊＊、Vq₅ ^＊＊Coordinate conversion into three-phase voltage command value Vuvw₅ ^＊＊. Three-phase voltage command value Vuvw of 5 th order₅ ^＊＊Three-phase voltage command value Vuvw with fundamental wave by high-order voltage component superposition part 19^＊And (6) superposing.

The control block of the 7-stage current control system includes a 7-stage current command generating unit 72, a 7-stage current deviation calculating unit 73, a 7-stage dq converting unit 74, a 7-stage voltage command calculating unit 75, a conversion amount setting unit 76, a 7-stage voltage vector converting unit 77, and a three-phase converting unit 78. The structure of each control block is the same as that of the 5-step current control system. As a point to be noted, the 7 th-order dq conversion unit 74 converts the fundamental current deviations Δ Id and Δ Iq into a 7 th-order dq coordinate system based on "7 θ e" which is a 7-fold angle of the electrical angle θ e. Thus, the 7-step dq conversion unit 74 extracts the phase current 7-step component included in the actual current. Since the other points are the same as those of the 5-step current control system, the description thereof will be omitted.

Next, basic matters of the fundamental wave and the higher-order current control of the present embodiment will be described with reference to fig. 4 to 6.

The dq conversion of the phase current k-th order component from the fixed coordinate system to the dq coordinate system is represented by equation (1). ' φ d in formula (1)_k"represents the phase of the k-order component vector in dq coordinates with reference to the d-axis. Further, "Ir_k"denotes the amplitude of the current vector of the k-th order component.

(math formula 1)

In table 1, the correspondence between the order in the fixed coordinate system and the order in the dq coordinate system is represented based on equation (1).

(Table 1)

Fixed coordinate system	dq coordinate system
		1 st order	Direct current
5 th order	6 th order
		7 th order	6 th order
Order K	Order of (k-1)

Here, the order k other than 1 st order is represented by formula (2.1). In the formula (2.1), the case where n is 0 corresponds to 1 st order (fundamental wave). In addition, the case where n is 1 corresponds to the (-5) th order and the 7 th order.

k 1 ± 6n (n is a natural number) · (2.1)

In addition, in the case where the positive and negative of the order are not distinguished, the absolute value of k is represented by equation (2.2).

An | k | 1 ± 6n | 6n ± 1(n is a natural number) · (2.2)

The negative orders in table 1 have the following meanings.

In the fixed coordinate system, when the phase sequence of the three phases is opposite to the fundamental wave, the order is negative. For example, when the phase sequence of the fundamental wave is UVW, the order of the higher-order component whose phase sequence is UWV is represented by a negative sign.

In the dq coordinate system, when the rotation direction of the high-order component is the counterclockwise direction (left rotation), the order is positive, and when it is the clockwise direction (right rotation), the order is negative.

In general, the (k-1) th order of the dq coordinate system corresponds to the k th order of the fixed coordinate system. Specifically, the (-5) th order of the fixed coordinate system corresponds to the (-6) th order of the dq coordinate system, and the 7 th order of the fixed coordinate system corresponds to the 6 th order of the dq coordinate system. Therefore, the phase current (-5) -order component and the phase current 7-order component are advantageous for making a torque 6-order fluctuation in the three-phase alternating-current motor.

In fig. 2, the angle input to the 5 th dq converter 54 and the three-phase converter 58 corresponds to the "cos (k θ e) term" in expression (1) — 5 θ e ".

In fig. 4, the relationship between the fixed coordinate system and the dq coordinate system is illustrated with respect to the fundamental wave. The phase sequence of the fundamental wave in the fixed coordinate system is the order of UVW.

Let the amplitude of the dq-axis current vector be Ir₁The amplitude of the phase current is represented by { √ (2/3) } Ir₁. Further, the phase φ d of the dq-axis current vector is set to be in a reference of an electrical angle of 0 ° in fixed coordinates₁For example, the phase corresponding to the maximum U-phase current.

In fig. 5, regarding the phase current (-5) order component, the relationship of the fixed coordinate system and the 5 th-order dq coordinate system is illustrated. Since the phase sequence of the fixed coordinate system is UWV opposite to the fundamental wave, it is expressed by a negative order.

The 5 th order dq-axis current vector is rotated clockwise 6 times on the 5 th order coordinate every electrical cycle, centered at the end of the 1 st order dq-axis current vector. Let the amplitude of the dq-axis current vector corresponding to the radius of rotation be Ir₅The amplitude of the order component of the phase current (-5) is represented by { √ (2/3) } Ir₅。

In addition, the phase of the 5 th order dq axis current vector is represented as "-6 θ e + φ d₅". When the electrical angle of 0 DEG in the fixed coordinate is taken as the reference, the phase phi d₅For example, the phase corresponding to the maximum U-phase current.

The high-order component superimposed on the phase current appears in the dq-axis current as an alternating-current component corresponding to the order after dq conversion. The high-order dq conversion is a method of directly streaming and controlling high-order components superimposed on the phase current to a desired value.

As shown in fig. 6, in the present embodiment, the phase current in the fixed coordinate system is once converted into the dq coordinate system, and then converted into the high-order dq coordinate system. Fig. 6 corresponds to a diagram extracted from the control block relating to dq conversion and higher-order dq conversion shown in fig. 2. For convenience of explanation, the sign of "+/-" in the fundamental current deviation calculation unit 13 is opposite to that shown in fig. 2.

The conversion expression "fixed coordinate system → dq coordinate system → higher-order dq coordinate system" corresponding to fig. 6 is represented by expression (3).

(math figure 2)

In FIG. 6, in the original signal, i.e., phase current, on the fundamental waveWith the higher order components superimposed. The fundamental wave is converted into a direct current by the actual current dq conversion unit 36. The fundamental current deviation calculation unit 13 calculates a fundamental current command value Id^＊、Iq^＊Removed from the actual current after dq conversion. Thereby, high-order components of the alternating current are left. In the high-order dq conversion units (5 th and 7 th dq conversion units) 54 and 74, high-order dq conversion is performed on the high-order component of the alternating current to convert the alternating current into a direct current.

The above is a description of fundamental matters regarding the fundamental wave and the high-order current control. In this way, in the present embodiment, the high-order components of a certain order are directly fluidized by high-order dq conversion. Thus, the current controller 30 of the present embodiment performs feedback control on the high-order current command value of each order.

Next, referring to fig. 7A and 7B, the technical meaning of the filtering process using the command value filter 11 of the present embodiment will be described.

As shown in fig. 7A, in general, in motor control, the calculation period Tc _ trq of the torque command generator 20 is set to be longer than the calculation period Tc _ I of the current controller 30. Therefore, the calculated torque command is input to the current controller 30 which calculates in a stepwise manner with a relatively short period. Further, the responsiveness (calculation cycle of current control) of the current controller 30 is faster than the calculation cycle of the torque command. Therefore, when the current controller 30 uses the input from the torque command generator 20 (the input torque command) as it is for control, the actual torque is output from the MG80 in a stepwise manner. As a result, for example, when applied to a hybrid vehicle, there is a possibility that drivability may be affected.

Therefore, in the present embodiment, the torque command value Trq is set by the command value filter 11 of the current controller 30^＊The filter process of response smoothing of (1). That is, the current controller 30 of the present embodiment performs "smoothing processing".

As shown in fig. 7B, the torque command value Trq before the filter processing^＊Contains high frequency components in all frequency ranges. On the other hand, the torque command value Trq after the filtering process by the command value filter 11^＊Where the spectrum of f is to be filteredThe pre-processing torque command value Trq^＊The high frequency components contained in the (C) are removed. Although there is a slight error due to the current response, the filtered torque command value Trq^＊The spectrum of f is close to the spectrum of the actual torque.

In fig. 7B, the spectrum range of the actual torque is shown by a solid line box, and the filtered torque command value Trq is shown by a broken line box^＊Illustration of spectral range of f. The above-mentioned box indicates a range in which the main spectrum exists within the box.

As described above, in the present embodiment, the frequency spectrum of the filtered torque command value Trq _ f mainly contains the first order component and does not contain the high frequency component of 5 th order or more. Therefore, current controller 30 of the present embodiment uses current command value Id generated from filtered torque command value Trq _ f^＊、Iq^＊Thus, the high-order components included in the actual currents Id and Iq can be extracted.

Patent document 1 (japanese patent No. 3809783) discloses a technique for extracting high-order components using a high-pass filter and a current response model. However, when high-pass filtering is used, there is a problem that the fundamental wave component remains. In addition, when the current response model is used, the calculation load of the filter calculation processing portion increases.

Therefore, in the present embodiment, the torque command value Trq after the filtering process by the command value filter 11 is selected^＊Current command value Id generated by _ f^＊、Iq^＊The difference from the actual currents Id and Iq, a high-order component is extracted. Accordingly, the MG control device 10 according to the present embodiment can avoid the problem of the residual of the fundamental wave component and the like in the case of using the high-pass filter. Further, the MG control device 10 according to the present embodiment can appropriately extract the higher-order component without increasing the calculation load as in the case of using the current response model. As a result, the MG control device 10 of the present embodiment can shorten the processing time.

Next, the technical meaning of the high-order vector conversion processing by the 5 th order voltage vector conversion unit 57 and the 7 th order voltage vector conversion unit 77 according to the present embodiment will be described with reference to fig. 8A to 8C.

As shown in fig. 8A, in general, the phase of the voltage vector and the phase of the current vector do not match in the dq-axis coordinate, and there is a phase difference Δ Φ. When the phase difference Δ Φ between the high-order voltage vector and the high-order current vector becomes large, the motor control may become unstable depending on the structure and characteristics of the ac motor.

In the fundamental current control, a d-axis voltage command value is calculated from a q-axis current deviation and a q-axis voltage command value is calculated from a d-axis current deviation in a voltage equation of a feedforward term. Thus, there is known a non-interference control in which the d-axis component and the q-axis component are independently controlled in the fundamental current control. However, in the high-order current control, no disturbance-free control is considered.

Therefore, in the present embodiment, the phase of the high-order voltage vector such as 5 th order or 7 th order is corrected to match the phase of the current vector by rotating the vector. The high-order vector conversion processing is performed on the high-order current vector deviation input to the 5 th-order voltage command operation unit 55 and the 7 th-order voltage command operation unit 75. Alternatively, the high-order vector conversion processing is performed on the high-order voltage command vector calculated through feedback control.

In the high-order vector conversion processing, amplitude conversion may be performed to change the amplitude of the vector at the same time as the rotation conversion.

In fig. 8B, a case where only the rotation conversion (R) is performed in the high-order vector conversion processing is exemplified. In fig. 8C, a case where the rotation conversion (R) and the amplitude conversion (G) are simultaneously performed in the high-order vector conversion process is exemplified. In addition, in general, the rotation angle phi_kRepresenting a rotation transformation of a vector of order k.

As shown in fig. 2, in the present embodiment, the 5 th order voltage command vector Vd calculated by the 5 th order voltage command calculation unit 55 is used₅ ^＊、Vq₅ ^＊And 7-order voltage command vector Vd calculated by 7-order voltage command calculation unit 75₇ ^＊、Vq₇ ^＊And (4) rotating. High order vectors of 5 th order voltage vector conversion section 57 and 7 th order voltage vector conversion section 77The conversion process is expressed by equation (4.1) and equation (4.2) including a rotation matrix, respectively.

(math figure 3)

On the other hand, Δ Id for 5 th order current vector deviation₅、ΔIq₅And 7 th order current vector deviation Δ Id₇、ΔIq₇In the method of performing the high-order vector conversion processing, the high-order current vector deviation is rotated and then feedback control is performed. In the current controller of the above-described embodiment, the arrangement of the control blocks "55, 75" and "57, 77" is reversed with respect to the arrangement shown in fig. 2. Further, the name of the control block of "55, 75" instead of the "5 th/7 th order voltage vector conversion section" becomes "5 th/7 th order vector deviation conversion section". The technique of the present invention includes a control block that performs the high-order vector conversion processing using the above-described two methods, and is referred to as a "high-order vector conversion unit".

The phase difference Δ Φ between the voltage vector and the current vector is caused by the inductance of the MG80 and the induced voltage of the rotor. Therefore, the phase difference Δ Φ depends on the operation state such as the current value and the rotation speed. The conversion

amount setting unit

56, 76 of the present embodiment sets, for example, a previously measured fundamental wave current command value Id^＊、Iq^＊And the relationship between the rotational speed ω and the phase difference Δ Φ and the amplitude ratio is stored in advance as a map (data with a correspondence relationship). The conversion

amount setting units

56 and 76 set the conversion amount based on the fundamental wave current command value Id^＊、Iq^＊And a rotation speed omega, and the rotation angle phi of the rotation conversion, which is the conversion amount of the high-order vector conversion processing, is obtained by referring to a table or the like₅、φ₇And gain G of amplitude conversion₅、G₇The setting is performed.

In addition, the fundamental wave current command value Id is replaced^＊、Iq^＊The conversion

amount setting units

56 and 76 may use the actual currents Id and Iq, the torque detection value of the MG80, and the like as parameters for referring to the map.

As described above, in the present embodiment, command vector Vd is set to a high-order voltage₅ ^＊、Vq₅ ^＊、Vd₇ ^＊、Vq₇ ^＊The high-order vector conversion processing is performed so that the phases of the high-order voltage vector and the high-order current vector coincide. Thereby, the MG control device 10 of the present embodiment can stabilize the motor control. Vector deviation Δ Id for high-order current inputted to 5-order voltage command operation unit 55 and 7-order voltage command operation unit 75₅、ΔIq₅、ΔId₇、ΔIq₇The same applies to the case where the high-order vector conversion processing is performed.

In the present embodiment, the rotation angle Φ to be converted to rotation is set according to the operating state such as the current value and the rotation speed₅、φ₇And gain G of amplitude conversion₅、G₇The setting is performed. Accordingly, the response of the feedback control by the MG control device 10 of the present embodiment can be constant regardless of the operating point.

(other embodiments)

(a) The current controller of other embodiments may not include a command value filter. For example, when there is still a margin in the processing capacity of the MG control device, the high-order component may be extracted using the current response model. In a system in which the calculation cycle of the torque command generator is the same as the calculation cycle of the current controller, the torque command value Trq input to the current controller^＊There is a possibility that high frequency components are not contained. In the above case, the torque command value Trq is set to a value not containing a high frequency component^＊Generated current command value Id^＊、Iq^＊The high-order component is extracted as appropriate from the difference between the actual current Id and the actual current Iq.

(b) In the above embodiment, in the MG control device 10 applied to the drive system of the MG80 that is a three-phase alternating-current motor, the current controller 30 controls the 5 th order and 7 th order components as the specific order represented by the absolute value. In another embodiment, the current controller may control components of respective orders such as 11 th, 13 th, 17 th, and 19 th, which correspond to the case where n ═ 2 and 3 · · in equation (2.2).

(c) The ac motor driven in the system to which the technique of the present invention is applied may not function as a generator as in the MG80 of the above-described embodiment. The ac motor is not limited to a permanent magnet type synchronous motor, and may be an induction motor or another synchronous motor. The number of phases of the rotating electric machine of the multiphase ac motor may be four or more. The specific order of the high-order component from the actual current, which is the object of extraction, differs depending on the number of phases.

(d) The ac motor control device of the present invention is not limited to the MG drive system of the hybrid vehicle or the electric vehicle, and can be applied to ac motor drive systems for various applications such as general machinery.

As described above, the present invention is not limited to the above embodiments, and can be implemented in various ways without departing from the scope of the present invention.

Description of the symbols

100. MG control device (control device for AC motor),

30. the current controller,

40. inverter,

41 to 46. DEG C. a switching element,

55. 75 · 5 th/7 th order voltage command operation section (high order voltage command operation section),

56. 76. the transition amount setting section,

57. 77 · 5 th/7 th order voltage vector conversion section (high order vector conversion section),

80. MG (AC motor).

Claims

1. A control device for an alternating-current motor, comprising:

an inverter (40) that supplies the power converted by the operation of the plurality of switching elements (41-46) to a multi-phase alternating-current motor (80); and

a current controller (30) that controls the energization of the alternating-current motor by calculating a drive signal for driving the inverter by a fundamental current control that causes a 1 st order component of the fed-back actual current to coincide with a fundamental current command vector on dq coordinates and a higher-order current control that causes a higher-order component of 1 or more specific orders extracted from the fed-back actual current to coincide with a higher-order current command vector on higher-order dq coordinates,

the current controller has:

a high-order voltage command calculation unit (55, 75), wherein the high-order voltage command calculation unit (55, 75) calculates a high-order voltage command vector by feedback control in which a high-order dq conversion value of the high-order component of the specific order extracted from the actual current is matched with a high-order dq-axis current command value; and

and a high-order vector conversion unit (57, 77) that performs high-order vector conversion processing including rotation conversion for rotating the high-order vector so that the phase of the high-order current vector coincides with the high-order voltage vector on the high-order dq coordinate, with respect to the high-order current vector deviation input to the high-order voltage command calculation unit or the high-order voltage command vector calculated by the high-order voltage command calculation unit.

2. The control apparatus of an alternating current motor according to claim 1,

the current controller includes a conversion amount setting unit (56, 76), and the conversion amount setting unit (56, 76) sets a conversion amount in the high-order vector conversion processing, that is, a rotation angle of the rotation conversion, based on a fundamental wave current command value and a rotation speed of the AC motor.

3. The control apparatus of an alternating current motor according to claim 1,

the higher order vector conversion processing includes, in addition to the rotation conversion, amplitude conversion in which a gain other than 1 times is multiplied by the amplitude of the higher order vector.

4. A control apparatus of an AC motor according to claim 3,

the current controller includes a conversion amount setting unit (56, 76), and the conversion amount setting unit (56, 76) sets a conversion amount in the high-order vector conversion processing, that is, a rotation angle of the rotation conversion and a gain of the amplitude conversion, based on a fundamental wave current command value and a rotation speed of the alternating current motor.

5. The control device of an AC motor according to any one of claims 1 to 4,

the polyphase alternating current motor is a three-phase alternating current motor,

the current controller extracts, as the high-order component of the specific order, a high-order component of 6n ± 1 order, where n is a natural number.